U.S. patent number 5,703,462 [Application Number 08/679,587] was granted by the patent office on 1997-12-30 for inductive coupler assembly having its primary winding formed in a printed wiring board.
This patent grant is currently assigned to Delco Electronics Corp.. Invention is credited to Scott D. Downer, George R. Woody.
United States Patent |
5,703,462 |
Woody , et al. |
December 30, 1997 |
Inductive coupler assembly having its primary winding formed in a
printed wiring board
Abstract
An inductive coupler having an antenna and primary winding
formed as part of a single structure that can be readily and
consistently produced using printed wiring board manufacturing
techniques. The coupler has the primary winding and antenna are
formed as part of a printed wiring board. A coupler housing having
two mating coupler halves secures a center magnetic core and the
printed wiring board therebetween. The coupler housing also secures
a cable that is coupled between selected printed circuit layers of
the primary winding and a power source for coupling energy to the
charging coupler.
Inventors: |
Woody; George R. (Redondo
Beach, CA), Downer; Scott D. (Torrance, CA) |
Assignee: |
Delco Electronics Corp.
(Kokomo, IN)
|
Family
ID: |
24727504 |
Appl.
No.: |
08/679,587 |
Filed: |
July 15, 1996 |
Current U.S.
Class: |
320/108;
336/DIG.2; 320/109 |
Current CPC
Class: |
H01F
38/14 (20130101); Y10S 336/02 (20130101) |
Current International
Class: |
H01F
38/14 (20060101); H02J 007/04 () |
Field of
Search: |
;320/2
;336/200,232,DIG.2 ;219/670,672,675 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wong; Peter S.
Assistant Examiner: Law; Patrick B.
Attorney, Agent or Firm: Navarre; Mark A.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. An inductive charging coupler for use with inductive charging
apparatus comprising a power source and a charge port disposed in
an electric vehicle that is coupled to a battery of the electric
vehicle, and wherein the coupler is insertable into the charge port
to couple power from the power source to charge the battery of the
electric vehicle, said coupler comprising:
a center magnetic core;
a printed wiring board disposed around the center magnetic core
that comprises a plurality of printed circuit layers that each have
a predetermined printed circuit pattern that together form a
primary winding, and an antenna formed as an electrical trace on a
selected one of said printed circuit layers;
a cable coupled between selected printed circuit layers of the
primary winding and a power source for coupling energy to the
charging coupler 20; and
a coupler housing that has two mating coupler halves that are
configured to provide a handle, and wherein the mating coupler
halves enclose the printed wiring board, secure the center magnetic
core, and secure the cable in the handle.
2. The inductive charging coupler of claim 1 wherein said cable
includes a coaxial communications cable coupled to said antenna to
couple communications signals between said power source and said
charge port.
3. An inductive charging coupler for use with inductive charging
apparatus comprising a power source and a charge port disposed in
an electric vehicle that is coupled to a battery of the electric
vehicle, and wherein the coupler is insertable into the charge port
to couple power from the power source to charge the battery of the
electric vehicle, said coupler comprising:
a center magnetic core;
a printed wiring board disposed around the center magnetic core
that comprises a plurality of printed circuit layers that each have
a predetermined printed circuit pattern that together form a
primary winding;
a cable coupled between selected printed circuit layers of the
primary winding and a power source for coupling energy to the
charging coupler 20;
a coupler housing that has two mating coupler halves that are
configured to provide a handle, and wherein the mating coupler
halves enclose the printed wiring board, secure the center magnetic
core, and secure the cable in the handle; and
a plurality of grounding clips disposed in the handle that engage
outer shielding of the cable.
4. The inductive charging coupler of claim 3 wherein the grounding
clips are comprised of tinned copper.
5. An inductive charging coupler for use with inductive charging
apparatus comprising a power source and a charge port disposed in
an electric vehicle that is coupled to a battery of the electric
vehicle, and wherein the coupler is insertable into the charge port
to couple power from the power source to charge the battery of the
electric vehicle, said coupler comprising:
a center magnetic core;
a printed wiring board disposed around the center magnetic core
that comprises a plurality of printed circuit layers that each have
a predetermined printed circuit pattern that together form a
primary winding;
a cable coupled between selected printed circuit layers of the
primary winding and a power source for coupling energy to the
charging coupler 20;
a coupler housing that has two mating coupler halves that are
configured to provide a handle, and wherein the mating coupler
halves enclose the printed wiring board, secure the center magnetic
core, and secure the cable in the handle, the mating coupler halves
having molded spring fingers formed thereon for holding the center
magnetic core in the coupler housing.
Description
BACKGROUND
The present invention relates generally to inductive couplers, and
more particularly, to an improved inductive coupler having a
printed wiring board that forms a primary winding and antenna.
The assignee of the present invention designs and manufactures
inductive charging systems for use in charging electric vehicles.
The charging system employs a charge port into which an inductive
coupler is inserted to charge the electric vehicle. The inductive
coupler forms a primary winding of a transformer and the charge
port forms a secondary winding of the transformer. The charging
system couples high frequency, high voltage AC power to the
transformer which charges propulsion batteries of the vehicle.
A prior primary winding developed for use in the inductive coupler
had a manufacturing process that was complex, labor intensive,
expensive, and prone to failures. An antenna portion of the coupler
was previously made using coaxial wire that was trimmed and
soldered with an extra outer braid layer to form a dipole antenna.
This was not a repeatable process and caused a wide variation in
performance. Therefore, it would be an improvement in the an to
have a coupler design that is readily manufacturable and provides
consistent performance.
Accordingly, it is an objective of the present invention to provide
for an improved inductive coupler for use with an inductive charger
system that is used to charge propulsion batteries of an electric
vehicle. It is a further objective of the present invention to
provide for an improved inductive coupler having a printed wiring
board that forms a primary winding and antenna.
SUMMARY OF THE INVENTION
To meet the above and other objectives, the present invention
provides for an improved inductive coupler by combining an antenna
and primary winding into a single structure that can be readily and
consistently produced using conventional printed wiring board (PWB)
manufacturing techniques. The primary winding and antenna are
formed as part of a printed wiring board of the coupler.
Consequently, the inductive coupler is less costly to produce and
improves the overall performance of charging systems in which it is
used.
The coupler, in conjunction with a charge port of the charging
system, is medium by which electric power is transferred by means
of inductive coupling. The shape of the coupler is esthetically
pleasing and functional. The coupler is somewhat thicker that
previously used designs. The coupler houses the printed wiring
board which forms a primary winding and communication antenna, a
magnet that is used to activate a switch in the mating charge port,
and a ferrite puck that is visible from the outside of the coupler.
The shape of the puck and primary winding gives the coupler its
characteristic disc shape.
The shape of the coupler is a product of the functionality of its
end use. The internal construction is different from previous
coupler designs in that it utilizes the printed wiring board as the
primary winding as opposed to more costly bussbar type folded turns
and spiral pressed turns. A 915 MHz band carrier antenna is formed
as part of the printed wiring board. Heretofore, a separate
labor-intensive dipole antenna made from a coaxial cable was used.
The printed wiring board meets safety requirements for insulation
integrity, voltage spacing, and flame resistance. Early couplers
were much thinner which did not provide adequate cooling needed for
high power charging.
The present coupler design has been chosen as a standard interface
for use in charging systems developed by the assignee of the
present invention. It has a thicker cross section that can
accommodate coupler designs within its envelope to provide charging
capacities up to 130 KW of power or higher. In addition, the
location of its grounding shield was improved by moving the
termination of the outer grounding shield closer to the power leads
of the primary winding which improved EMI compatibility.
The present invention is intended for use in inductive coupling
transformers for Magnecharge.TM. electric vehicle charging systems
manufactured by the assignee of the present invention. The
Magnecharge electric vehicle charging system previously used a
coupler design that was too thin to be used for higher charge rates
and had a primary winding that was based on a pressed spiral copper
configuration that was laminated with insulation. The present
invention as implemented saves over $100 in material and labor
costs over the previous coupler design.
The thicker coupler design allows heat exchangers to be installed
in charger models used for higher power charging levels. A thin
cross section heat exchanger causes pressure drops across the
coupler that are too high to be practical. The thicker cross
section is also compatible with lower charge rate charger models,
that provide power output of 6.6 KW or less, which do not require a
heat exchanger to cool the primary winding. In addition, there are
tactile feel features on the side of the coupler that comprise
conductive plastic strips at the base that contact copper fingers
in the charge port to provide for EMI shielding. This is needed
because the thicker coupler requires a larger slot width in the
charge port, which can increase radiated emissions. The coupler
also has features that couple it to a locking mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
The various features and advantages of the present invention may be
more readily understood with reference to the following detailed
description taken in conjunction with the accompanying drawings,
wherein like reference numerals designate like structural elements,
and in which:
FIG. 1 is a block diagram that illustrates an inductive charging
system employing an inductive coupler in accordance with the
principles of the present invention that is used to charge
propulsion batteries of an electric vehicle;
FIG. 2 is a perspective view of the inductive coupler in accordance
with the present invention;
FIG. 3 is a side view of the inductive coupler of FIG. 2;
FIG. 4 is an exploded view of the inductive coupler of FIG. 2;
FIGS. 5a-5g illustrate printed wiring board layers employed in the
inductive coupler of FIG. 2; and
FIG. 6 illustrates how the layers of the printed wiring board are
attached to each other to form a four-turn winding.
DETAILED DESCRIPTION
Referring to the drawing figures, FIG. 1 is a block diagram that
illustrates an inductive charging system 10 employing an inductive
charging coupler 20 or charge probe 20 in accordance with the
principles of the present invention. The inductive charging system
10 is comprised of a power source 13 that is coupled by way of a
power cable 14 to the inductive charging coupler 20. The inductive
charging coupler 20 is designed to be inserted into a charge port
15 located in an electric vehicle 12 (indicated by the dashed
arrow). The inductive charging coupler 20 comprises a primary of a
transformer while the charge port 15 comprises the secondary
thereof. Once the inductive charging coupler 20 is inserted into
the charge port 15, power is transferred from the power source 13
to propulsion batteries 11 of the electric vehicle 12 under control
of a controller 16.
FIGS. 2 and 3 show perspective, side and exploded views,
respectively, of the inductive charging coupler 20. FIGS. 2 and 3
also show the characteristic shape of the coupler 20. The inductive
charging coupler 20 comprises a plastic coupler housing 22 that has
two mating coupler halves 22a, 22b that are configured to provide a
handle 23. The inductive charging coupler 20 has a center magnetic
core 24 or "puck" 24, that may be comprised of ferrite, for
example. A primary winding 25 is disposed around the center
magnetic core 24 and is formed as a plurality of layers of a
printed wiring board 40. Details of the printed wiring board 40
will be discussed with reference to FIGS. 5 and 6. A charger cable
26, or other current carrying means 26, is coupled to the primary
winding 25 and to the power source 13 for coupling energy to the
charging coupler 20. The charging coupler 20 is designed to be
inserted into an opening in the charge port 15 in order to couple
power to the batteries 11 from the power source 13. A plurality of
magnets 33 are provided that are used to activate a proximity
switch (not shown) located in the charge port 15 that is used to
provide an indication that the charge coupler 20 is properly
inserted into the charge port 15. An antenna 35 is formed as an
electrical trace on the printed wiring board 40. The antenna 35 is
used to couple communications signals between control electronics
in the charging system and electronics in the electric vehicle 12.
The coupler 20 includes an opening 38a and a coupler stop 38b that
are employed to lock it into the charge port 15.
The mating coupler halves 22a, 22b of the inductive charging
coupler 20 enclose the primary winding 25 and the center magnetic
core 24, and secures the charger cable 26 in the handle 23. The
handle 23 includes a plurality of grounding clips 28 that engage
outer shielding 29 of the charger cable 26. Conductive plastic
strips 31 are disposed along an exterior portion of the coupler 20
between the handle 23 and the primary winding 25. The conductive
plastic strips 31 engage metallized electromagnetic interference
(EMI) fingers (not shown) on the charge port 15 when the coupler 20
is inserted into the charge port 15. A strain relief member 32
surrounds the charger cable 26 at a point where it exits the handle
23, and is secured by the two mating coupler halves 22a, 22b.
The coupler housing 22 may be made using an insertion molding
process. First the conductive plastic strip 31 is molded and then
inserted in the mold to make the entire coupler housing 22. The
coupler 20 is made in two halves 22a, 22b that are bonded,
ultrasonic welded, or hot plate welded together. The inside walls
of the coupler halves 22a, 22b are metalized so the coupler 20 is
completely shielded and can be connected internally to the shielded
outer shielding 29 of the charger cable 26 and to the conductive
plastic strip 31. The grounding clips 28 inside of the handle 23
make contact with the cable shielding 29 after the two coupler
halves 22a, 22b are joined together by adhesive or ultrasonic
welding methods. The conductive plastic strip 31 of the coupler 20
is then grounded to the outer braided 29. When the coupler 20 is
inserted into the charge port 15 located in the vehicle, the
conductive plastic strip 31 makes contact with the EMI fingers in
the charge port 15. The fingers are attached to a chassis ground of
the vehicle 12.
With specific reference to FIG. 4, it shows the internal assembly
drawing of the inductive charging coupler 20. The primary winding
25 is in the form of a printed wiring board 40 and is attached to
the charger cable 26 either by soldering or by screwing it down
with lugs. A coaxial RF cable 26a that is part of the charger cable
26 is stripped and soldered to the antenna 35 which is part of the
printed wiring board 40. The outer jacket of the charger cable 26
is stripped back to expose the outer braided shield 29. The shield
29 is sandwiched between two beryllium copper tabs that comprise
the grounding clips 28 that dig into conductive fibers of the
conductive plastic strips 31 which are insertion molded into the
coupler 20. The ferrite puck 24 is held in the center of the
coupler 20 with molded spring fingers 36 formed in the mating
coupler halves 22a, 22b. The two magnets 33 disposed in the coupler
20 close the proximity switch in the charge port 15 upon insertion
of the coupler 20 therein. The switch sends a signal to vehicle
electronics that the coupler 20 has been inserted into the charge
port 15.
The coupler 20 incorporates a number of features that are described
with reference to other patents and patent applications of the
present assignee. The coupler 20 employs the conductive plastic
strips 31 for EMI shielding as is described in U.S. Pat. No.
5,457,378 issued Oct. 10, 1995, entitled "Electromagnetically
Shielded Inductive Charging Apparatus", tactile feel indents 37 as
are described in U.S. Pat. No. 5,506,489, issued Apr. 2, 1996
entitled "Inductive Coupler Having a Tactile Feel", and locking
provisions comprising the opening 38a and coupler stop 38b as are
described in copending U.S. patent application Ser. No. 08/703,277,
filed Aug. 26, 1996, entitled "Charger Locking Mechanism". The
coupler has a thickness of 0.600 inches which has been chosen as a
standard thickness for a standard mating charge port. U.S. Pat. No.
5,434,493, filed Jul. 18, 1995 entitled "Fixed Core Inductive
Charger" describes a typical fixed inductive charge port 15 with
which the present coupler 20 may be used. The coupler 20 also has a
raised step 39 for the location of the conductive strip so EMI
fingers inside the port 15 will not rub across the whole face of
the coupler 20, which minimizes unnecessary wear.
FIGS. 5a-5g illustrate artwork for layers 41-47 of the printed
wiring board 40 employed in the inductive coupler 20 of FIG. 2.
This type of artwork is also used for the secondary turns located
in the charge port 15. FIG. 6 illustrates how the layers 41-47 of
the printed wiring board 40 are attached to each other to form a
four-turn primary winding 25. This process can be used to increase
or decrease the number of turns simply by adding or deleting board
layers.
Thus, an improved inductive coupler having a primary winding and an
antenna integrated into a printed wiring board and which may be
used with an inductive charger system that is used to charge
propulsion batteries of an electric vehicle has been disclosed.
It is to be understood that the above-described embodiment is
merely illustrative of some of the many specific embodiments which
represent applications of the principles of the present invention.
Clearly, numerous and varied other arrangements may be readily
devised by those skilled in the art without departing from the
scope of the invention.
* * * * *